Ventilation system for high-rise structures

ABSTRACT

A ventilation system for providing fresh outdoor directly to each floor through an intake damper on the floor and for admitting only as much air as is required to meet the required outdoor air requirements when the temperature of the outdoor is at extreme ambient temperatures. The system utilizes a compartment unit on each floor and a plurality of VAV&#39;s which are located in zones on the floor for achieving desired temperatures in each zone by combining the recirculating air with the outdoor fresh air for delivering to the VAV&#39;s at about 55° F.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a regular application of U.S. application 60/829,648 entitled VENTILATION SYSTEM FOR HIGH-RISE STRUCTURES filed Oct. 16, 2006, from which this application claims priority, the entirety of which is incorporated herein by reference.

FIELD OF THE INVENTION

Embodiments of the invention relate to ventilation systems for structures and more particularly to structures having a plurality of zones on a plurality of separate floors which require ventilation and temperature control.

BACKGROUND OF THE INVENTION

As shown in FIGS. 1A and 1B, conventional ventilation systems typically comprise a large single main duct which extends from a roof to a base of a high-rise building. Air at ambient temperature is drawn into the duct, such as by large fans, at the roof and during cold seasons is heated to about 55° F., often to prevent condensation forming in the duct. The air is drawn from the main duct to individual compartment units on each floor. At each floor, the compartment unit or air handler delivers the primary air, which comprises a mixture of outdoor air from the main duct and re-circulated return air from the floor, to one or more variable air volume (VAV) units which service individual zones on the floor. The one or more VAV boxes then circulate the primary air into each thermostatically controlled zone to maintain the desired temperature. Excess air volumes are exhausted at the roof. The main duct provides fresh air to all the floors. Due to volumes of air required, the main duct is sized to provide a maximum amount of fresh air required to meet the minimum fresh air volumes only.

The VAV boxes are typically thermostatically or sensor-controlled and regulate the quantity of conditioned air, typically at 55° F., which is supplied to each zone.

Typically, standards require that outdoor air be provided at a minimum of about 20 cfm/person or 1 cfm/square foot. Typical high-rises often have about 15,000-20,000 square feet per floor or more and thus, large volumes of circulating air of about 15,000-20,000 cfm/floor or more are required. Optional monitoring, using other sensors such as CO₂ sensors, is known to regulate the amount of outdoor air based on actual loads per zone and therefore the amounts required may be lower than design loads when the number of people in the building is reduced.

At moderate temperature, such as the typical design temperature of 55° F., theoretically all air provided to the VAV's could be fresh air. Unfortunately, the main duct cannot be sized large enough for this scenario. Accordingly, energy is typically expended to cool recirculating air.

In addition to the large amounts of energy utilized to draw the large volumes of air required into the main duct and to exhaust excess air from the building, as well as the energy required to heat the air delivered to the main duct, particularly during fall and winter seasons, energy is also consumed in either heating or re-cooling the air at each compartmental unit and/or VAV to mix with recirculating air therein to provide desired ambient temperatures at the plurality of zones on each of the floors.

There is interest in the industry in providing a ventilation system which meets the requirements for fresh air supply to all zones in a high-rise building while minimizing energy consumption.

SUMMARY OF THE INVENTION

A novel ventilation system utilizes a damper on each floor which is fluidly connected through an external wall of each floor to the outdoors for directly admitting fresh outdoor air to the floor to satisfy regulated outdoor air requirements and to provide conditioned air at a design temperature of about 55° F. to conventional thermostatically or sensor-controlled distributors, such as VAV's or about 65° F. through controlled variable diffusers from a floor plenum, situated in zones on the floor.

When ambient temperatures are about the design temperature, no additional energy is expended to heat and or cool the air circulated to the distributors and the entirety of the air provided can be admitted through the intake damper which is sized accordingly.

When temperatures are very low or very high, only sufficient outdoor air to meet the minimum fresh air requirements is admitted and is mixed with recirculating air from the zones in the floor at a compartment unit for providing conditioned air at about 55° F. to the VAV's. At extreme temperatures, the conditioned air may need to be further cooled, using heat exchangers at the compartment unit or heated, typically at the VAV's, to satisfy zonal temperature requirements.

Therefore in a broad aspect of the invention a ventilation system for a high rise building having a plurality of conditioned floors, comprises: a compartment unit at each of the plurality of conditioned floors for mixing outdoor air and returned air therein for delivering conditioned air to each floor at a design temperature; an intake damper at each of the plurality of floors for directly connecting between the compartment unit and the outdoors, each intake damper directly admitting outdoor air from the outdoors to the compartment unit and capable of admitting a volume of outdoor air up to a total volume of conditioned air for the floor; one or more distributors on each conditioned floor for receiving the conditioned air from the compartment unit at the design temperature and for controlling the amount of conditioned air delivered to each of one or more zones on the conditioned floor so as to achieve a desired zonal temperature in the one or more zones; and an exhaust damper for each conditioned floor for exhausting excess air in an amount equal to or less than the admitted outdoor air.

In an embodiment of the invention the distributors are conventional variable air volume boxes, which deliver the conditioned air from the compartment unit to the zones on the floor under the control of a thermostat for achieving a desired temperature in each of the zones. Re-heat coils may be provided in the VAV's for heating the conditioned air to meet zonal temperature requirements. Similarly, heat exchangers in the system may be used to cool the conditioned air for delivery to the zones on the floor.

In an embodiment of the invention wherein the distributors are zonally controlled variable diffusers connecting the zone to a floor plenum, conditioned air is provided to the floor plenum at about 65° F. and the recirculated air is returned to the compartment unit through a ceiling plenum.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a longitudinal sectional schematic view of a conventional high-rise ventilation system according to the prior art;

FIG. 1B is a side sectional view according to FIG. 1A;

FIG. 2A is a longitudinal sectional schematic view of a high-rise ventilation system according to an embodiment of the invention;

FIG. 2B is a partial longitudinal sectional schematic view of a bottom of the high-rise according to FIG. 2A;

FIG. 3A is a partial longitudinal view of a plurality of conditioned floors of a high-rise building having a central ventilation system arrangement according to one embodiment of the invention;

FIG. 3B is a plan view of a conditioned floor according to FIG. 3A;

FIG. 4 is a plan view of a floor of a high-rise building having a perimeter ventilation system arrangement according to one embodiment of the invention;

FIG. 5 is a graphical representation of the approximate amounts of outdoor air required at a variety of ambient temperatures to permit maintaining both minimum outdoor air requirements and desired temperatures at each zone; and

FIG. 6 is a side sectional schematic view of a raised floor plenum according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Having reference again to FIGS. 1A and 1B, a conventional prior art ventilation system 1 typically comprises a single large duct 2 which extends from a roof 3 of a high-rise building to a base 4 of the high-rise building through which fresh air FA, at ambient temperature, is drawn, such as by large fans at the roof 3. During cold seasons the fresh air FA in the duct 2 is heated to about 55° F. The 55° F. heated fresh air FA is thereafter distributed at each conditioned floor 5 (5 a, 5 b, 5 c . . . ) from the main duct 2 to a compartment unit 6 which also receives returned air RA from the conditioned floor 5 and utilizes the now-heated fresh air FA to condition the returned air RA for providing the minimum required amount of fresh air FA therein and to assist with temperature control in each of a plurality of individual zones located on the conditioned floor 5.

Having reference to FIGS. 2A and 2B and in one embodiment, a ventilation system 10 for a high-rise building comprises, on each conditioned floor 5, a fresh or outdoor air intake damper 11 which extends through an external wall of the conditioned floor 5 for fluidly connecting to the outdoors adjacent the conditioned floor 5 to a compartment unit 6 for directly admitting fresh, outdoor air FA to the compartment unit 6. The compartment unit 6 mixes the outdoor air FA with return air RA returned from the conditioned floor 5 for forming conditioned air CA and then distributes the conditioned air CA to one or more distributors 12 on the conditioned floor 5 connected to one or more zones Z₁, Z₂, Z₃ . . . on the conditioned floor 5. In one embodiment, the distributors 12 are VAV's and each conditioned floor 5 has at least one VAV unit 12 per zone Z₁, Z₂, Z₃ . . . .

Wit reference also to FIG. 3A, the return air RA is collected in a ceiling plenum 23 for return to the compartment unit 6.

The system 10 further comprises an exhaust damper 13 fluidly connected to the outdoors for exhausting at least a portion of excess air EA from the floor typically in an amount equal to or less than the admitted outdoor air FA.

Further, the system typically comprises an exhaust duct 14 connecting between the floors 5 for venting at least a small amount of excess air EA to the base 4 of the building, typically the parkade.

Outdoor air FA is drawn directly from outdoors into each conditioned floor 5, at ambient temperature, through the outdoor intake damper 11 in amounts sufficient to satisfy at least a minimum requirement for outdoor air FA, which is typically about 1 cfm per square foot and at a minimum of about 20 cfm per person. The outdoor air FA is drawn into the compartment unit 6, such as by fans, where the outdoor air FA is mixed with return air RA from the conditioned floor 5 as required, for delivery as conditioned air CA by the VAV units 12 to each of the zones Z₁, Z₂, Z₃ . . . at a design temperature of 55° F. Each of the zones Z₁, Z₂, Z₃ . . . is independently thermostatically controlled and therefore each zone Z₁, Z₂, Z₃ . . . may require a different amount of conditioned air CA to be discharged to the air circulating in the zone Z₁, Z₂, Z₃ . . . to achieve a desired zonal temperature.

Typically at least the minimum 20 cfm/person is exhausted from each conditioned floor 5 to the parkade, such as through the exhaust duct 14, and a small amount of loss from each conditioned floor 5 occurs through elevator shafts 15 and the like. Any additional excess air EA is exhausted from each conditioned floor 5 through the exhaust damper 13 so as to balance a pressure on the conditioned floor 5.

For example, if a minimum required volume of outdoor air FA of 2000 cfm is drawn in through the intake damper 11, about 1500 cfm is exhausted to the parkade from bathrooms and generally from the conditioned floor 5 typically through the exhaust duct 14 and about 500 cfm is lost in the elevator shafts 15 and the like. In this case, no excess air would be exhausted through the exhaust damper 13.

Where 15,000 cfm of outdoor air FA is drawn in through the intake damper 11, the amount vented to the parkade, being about 1500 cfm is maintained as is the about 500 cfm which is lost in the elevator shafts 15 and the like. In this case, about 13,000 cfm of excess air EA remains to be exhausted through the exhaust damper 13. In embodiments of the invention, the exhaust damper 13 is a barometric damper.

As one of skill would understand, accommodations are made to meet local code regarding smoke evacuation. One such method is to extend the exhaust duct 14 to the roof 3 and to size the exhaust duct 14 accordingly so that smoke can be evacuated through the duct 14 when required.

As shown in FIG. 3B, and in one embodiment, the compartment unit 6 is centrally located on each conditioned floor 5 and provides conditioned air CA to the VAV units 12 in the surrounding zones Z₁, Z₂, Z₃ . . . .

Alternatively, as shown in FIGS. 3A and 4, the compartment unit 6 is located peripherally, typically adjacent the intake damper 11, and provides ventilation to the VAV units 12 in the surrounding zones Z₁, Z₂, Z₃ . . . .

As shown in FIG. 5, and in an example of a conditioned floor 5 of a building having about 15000 square feet, when the ambient temperature of the outdoor air FA is about 55° F., 100% of the total amount of air required for the conditioned floor 5 can be outdoor air FA. The outdoor air FA is delivered to the compartment unit 6 for delivery to the VAV units 12 and to the various zones Z₁, Z₂, Z₃ . . . for satisfying the ventilation, fresh air and temperature requirements. The entirety of the floors' ventilation requirement can be outside air FA and thus fresh outdoor air FA is drawn through the intake damper to meet the entire requirement. No additional energy is expended through heating or cooling the outdoor air FA at the compartment unit 6 or the VAV's 12.

As the ambient temperature of the outdoor air FA decreases, the amount of outdoor air FA drawn into the intake damper 11 is decreased. Only sufficient outdoor air FA is admitted and combined with re-circulating air in the compartment unit 6 so as to result in a distribution mixture of conditioned air CA at design temperature, being about 55° F., being discharged at the VAV units 12 in each zone Z₁, Z₂, Z₃ . . . and to meet the minimum outdoor air FA requirements. Clearly when the ambient temperatures are very low, such as about −20° F. or lower, only the minimum amount of outdoor air FA is drawn into the intake damper 11 to satisfy air quality requirements.

In order to result in a desired zonal temperature, one may need to heat the delivered 55° F. air at the VAV units 12. Typically, re-heating coils 16 are provided in some or all of the VAV units 12. Re-heating coils 16 may be provided only in VAV's 16 serving peripherally located zones Z₁, Z₂, Z₃ . . . and may be optionally used for heating the building at night. Alternatively, a heating coil may be provided at the compartment unit 6 for heating the air provided to the VAV's 12.

Added benefits and an even greater reduction in very cold outdoor air FA intake is possible by incorporating sensors 17, such as CO₂ monitors, into the ventilation system 10. The CO₂ monitors 17 sense the actual load in the building and can reduce the amount of outdoor air FA admitted below the minimum design amounts when the number of people in the building is reduced, such as on weekends and during the evening. Thus, energy savings are realized by reducing the amount of conditioning required.

When ambient air temperatures are above 55° F., the amount of outdoor air FA drawn into the intake damper 11 is similarly reduced to minimum levels to minimize cooling requirements for cooling the air delivered to the VAV's 12. A heat exchanger in the compartment unit 6 conditions the air, such as by cooling the returned air RA combined with the minimum amount of outdoor warmer air FA for delivery of conditioned air CA to the VAV units 12 in the zones Z₁, Z₂, Z₃ . . . at about 55° F. Typically, a chiller supplies cooling fluid to the heat exchangers in the compartment units 6, and is sized to accommodate maximum local ambient summer temperatures.

In one embodiment, sensors 17, such as CO₂ sensors, are incorporated into the ventilation system 10 for sensing actual occupant loads, the outdoor air FA intake through the intake damper 11 is controlled based on the actual load and may be reduced below a typical or design minimum which is calculated based on a hypothetical number of occupants. As previously stated, incorporating such sensors 17 is particularly advantageous for weekends, evenings and other times when occupant loads are typically very low. Rather than energize an entire ventilation system to satisfy only a few occupants on one or more of the floors 5 during these off-peak times, such as is done with many conventional systems, the ventilation system 10 according to embodiments of the invention is controlled by the sensors 17 to intake and potentially condition only the required amount of outdoor air FA for a particular conditioned floor 5 which is in use.

For example, a typical occupant density of 100 people per floor 5 may require a minimum of about 2000 cfm of fresh outdoor air FA. In conventional systems, the intake of the 2000 cfm would be maintained regardless the number of occupants, to meet the minimum design amount. However, in the ventilation system 10 according to this embodiment, if only 10 people were present on a floor, the CO₂ monitors 17 sense the reduced occupant load and reduce the minimum outdoor air FA intake to about 200 cfm which meets the minimum required amount of fresh outdoor air FA per person for that floor 5.

Having reference to FIG. 6, and in one embodiment, the distributor 12 comprises a floor plenum 20, situated at floor level, to which conditioned air CA from the compartment unit 6 is supplied. Variable flow diffusers 21 are provided in each zone Z₁, Z₂, Z₃ . . . and which can be adjusted individually by the occupants in each zone Z₁, Z₂, Z₃ . . . to control the flow of conditioned air CA to be released to the zone Z₁, Z₂, Z₃ . . . from the floor plenum 20. Return grilles 22 are mounted at the ceiling and air circulated though the zone Z₁, Z₂, Z₃ . . . is returned to a ceiling space 23 through the grilles 22. Returned air RA is returned to the compartment unit 6 as required and the excess air EA is exhausted to the outdoors through the exhaust damper 13 which is fluidly connected between the ceiling space 23 and the outdoors 24. In this embodiment, conditioned air CA is supplied to the floor plenum 20 at about 65° F. Thus, embodiments of the invention utilizing this embodiment provide even greater savings as cooling of air is not required unless the ambient temperature is above 65° F.

Optionally, additional embodiments are possible wherein heating and cooling of the air is augmented using geothermal heat sinks and cold sinks created for the purpose. In one such embodiment, cold outdoor air FA is exchanged in a heat exchanger with glycol circulated in the ground to freeze a portion of the ground situated below the building. The cold from the ground is subsequently circulated through the heat exchanger during summer to cool the air in the building. Similarly, a heat sink may be created by exchanging heat from the outdoor air FA during the summer with the ground so as to store heat for use in the winter. 

1. A ventilation system for a high rise building having a plurality of conditioned floors, the system comprising: a compartment unit at each of the plurality of conditioned floors for mixing outdoor air and returned air therein for delivering conditioned air to each floor at a design temperature; an intake damper at each of the plurality of floors for directly connecting between the compartment unit and the outdoors, each intake damper directly admitting outdoor air from the outdoors to the compartment unit and capable of admitting a volume of outdoor air up to a total volume of conditioned air for the floor; one or more distributors on each conditioned floor for receiving the conditioned air from the compartment unit at the design temperature and for controlling the amount of conditioned air delivered to each of one or more zones on the conditioned floor so as to achieve a desired zonal temperature in the one or more zones; and an exhaust damper for each conditioned floor for exhausting excess air in an amount equal to or less than the admitted outdoor air.
 2. The system of claim 1 wherein the one or more distributors are variable air volume boxes.
 3. The system of claim 1 further comprising an exhaust duct fluidly connected to each of the plurality of floors for exhausting at least some of the air from each of the plurality of floors to a base of the building.
 4. The system of claim 2 wherein the design temperature is about 55° F.
 5. The system of claim 1 wherein a re-heating coil is provided for heating the conditioned air for delivery to at least some of the one or more zones for achieving the desired zonal temperature.
 6. The system of claim 2 further comprising a re-heating coil in at least some of the variable air volume boxes on the conditioned floor for heating the conditioned air from the compartment unit for delivery to at least some of the one or more zones so as to achieve the desired zonal temperature.
 7. The system of claim 1 further comprising a heat exchanger for cooling the conditioned air to the design temperature when outdoor air temperatures are elevated.
 8. The system of claim 1 wherein the compartment unit is located centrally on the floor.
 9. The system of claim 1 wherein the compartment unit is located peripherally on the floor adjacent the intake damper.
 10. The system of claim 1 further comprising sensors for determining an actual occupant load for admitting fresh outdoor air sufficient to meet at least a minimum fresh air requirement based on the actual occupant load.
 11. The system of claim 10 wherein the sensors are CO₂ monitors.
 12. The system of claim 7 wherein the heat exchanger is in the compartment unit.
 13. The system of claim 1 wherein the distributor further comprises: a floor plenum for receiving the conditioned air from the compartment unit; one or more variable flow diffusers fluidly connected between the floor plenum and each of the one or more zones; a ceiling space fluidly connected to the compartment unit; and one or more return air grilles fluidly connected between each of the one or more zones and the ceiling space for re-circulating air from each of the one or more zones to the ceiling space for returning the re-circulated air to the compartment unit, and wherein the exhaust damper is fluidly connected to the ceiling space; and the one or more variable flow diffusers is adjustable for obtaining a desired zonal temperature.
 14. The system of claim 13 wherein the design temperature is about 65° F.
 15. The system of claim 13 further comprising one or more heating coils at the compartment unit for heating the conditioned air therein for delivery to the floor plenum. 